fathom - 5:39 pm on May 3, 2013 (gmt 0)
All summer I had posted repeatedly in the Google forums and the (mostly rude) posters there mostly focused on my content even though the penalty was on April 24.
You refused to look at sound reasoning and you started thread after thread about the same thing.
The date isn't the thing that matters... it's a single clue. There are other important clues you don't wish to look at:
1.) You rank exceptionally well for the phrases you have tons of same anchors - that's the opposite of PENGUIN
2.) You lost results on volumes of obscure longtail phrases that you also had minimal information about.
"THE DATE" is important because it showed you had more link juice before April 24 & less link juice after April 25 but that does not necessarily mean you yourself was damaged by PENGUIN... those linking to you had loses and that spilled over into your project... and you only lost your obscurity phrases which for each one maybe on a few clicks but collectively was a sizable amount.
That said, you can't fix your problem without fixing your content.